1. Field of the Invention
This invention relates to a digital signal recording and reproducing apparatus. Also, this invention relates to a recording medium.
2. Description of the Related Art
There is a known digital VTR (video tape recorder) including a rotary head via which a digital signal representative of information is recorded on a magnetic tape. During playback, the digital signal is reproduced from the magnetic tape via the rotary head. The speed of the magnetic tape and the rotational speed of the rotary head which occur during normal-speed playback are equal to those occurring in the recording mode of operation of the digital VTR.
In such a digital VTR, during the recording mode of operation, a magnetic tape is driven at a predetermined tape speed while a rotary head is rotated at a predetermined head speed. The predetermined tape speed and the predetermined head speed are fixed. Thus, the predetermined tape speed and the predetermined head speed can not be changed. Any special signal representing the speed of the magnetic tape and the rotational speed of the rotary head is not recorded on the magnetic tape. During a normal-speed playback mode of operation of the digital VTR, the magnetic tape is driven at the predetermined tape speed and the rotary head is rotated at the predetermined head speed as in the recording mode of operation.
A known analog VTR can selectively operate in either a normal time mode or a long time mode. The long time mode of operation can continue to record an information-representing signal on a magnetic tape for an interval equal to three times an interval available in the normal time mode of operation. In the analog VTR, during the recording of an information-representing signal on the magnetic tape, a control pulse signal is recorded on a control track extending along a longitudinal direction of the magnetic tape. The recorded control pulse signal has a period depending on whether the signal recording is implemented by the normal time mode or the long time mode. During playback, the analog VTR reproduces a control pulse signal, and decides whether an information-representing signal is of the type recorded by the normal time mode or the long time mode.